Near-Field Radiative Heat Transfer around the Percolation Threshold in Al Oxide Layers

Abstract

We present a theoretical calculation of the near -field radiative heat transfer (NFRHT) around the percolation threshold of oxide layers that forms on aluminum surfaces. As this layer grows the volume fraction of Al decreases and that of Al2O3 increases. During this process, the Al plasmon response degrades, and the surface phonon modes of Al2O3 become active, thus increasing the spectral radiative heat flux. This occurs when the content of aluminum oxide on the surface approaches 67% in volume, which corresponds to the percolation threshold according to the Bruggeman effective medium theory. This oxidation fraction defines two regions: for volume fractions below the percolation threshold, the total heat flux is lower than that of unoxidized Al; otherwise, it is larger. Thus, oxidation considerably affects both the spectral and total radiative heat transfer.

Near-field radiative heat transfer between high-temperature superconductors

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Enhancement of near-field thermal radiation between composite materials with gradient plasmonic nanoparticles

“…Conversely, NFRHT can be controlled and highly adjusted by composite materials (CMs), which are artificial three-dimensional structures composed of hosts and inclusions, and have been widely studied and applied in NFRHT due to their support in various optical modes, multi-dimensional controllability and ease of production. [24][25][26] Taking advantage of these characteristics, Gao et al developed near-field thermal diodes with CMs that exhibit high rectification efficiency and can operate even at small temperature differences. 24,25 J. Fang et al presented a near-field thermal transistor in a system combining composites and phasechange materials.…”

Resonant enhancement of the near-field radiative heat transfer in nanoparticles

“…In composite materials, the dielectric function can be modified by a suitable combination of host and inclusions 12,13 . The simplest configuration of a composite is a layered media that can give rise to the different surface and hyperbolic modes [14][15][16][17][18] , which allow the enhancement of the radiative heat transfer at subwavelength scales 19,20 .…”